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1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

fuel problem????

Old Sep 11, 2003 | 09:59 AM
  #16  
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fuel problem????

Thanks, I'm tinkering everyday... getting it to idle a little better but still no wide open...now yesterday fuel filter filled up???? I'm checking compression today, the carb instruction book suggested that bad cylinder comp. could be the problem..did the fuel in jar test and fuel is getting up there..Sometimes if I play with pedal it will rev up but still very sporadic....coul d the gasket between intake and carb be too thick? It came with several and I used on like the one that came off the old one? Just wondering if that could make any difference.. Thanks again, Jerry
 
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Old Sep 11, 2003 | 11:54 AM
  #17  
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fuel problem????

shouldn't matter how thick it is as long as it lins up and seals.
 
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Old Sep 11, 2003 | 01:52 PM
  #18  
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fuel problem????

can you sllloooowwly give it throttle without killing it? If so, it is probably your accelerator pump. My holley had a gasket slightly misaligned, and i wasnt getting hardly any gas when I had to get up and go, and she would stall out an die.

To check, turn the truck off, and look down the throat of the carb, and floor the throttle. about a teaspoon of gas should squirt from the bowl side of the throat onto the venturi.
 

Last edited by MuchToMyDelight; Sep 11, 2003 at 01:55 PM.
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Old Sep 12, 2003 | 05:30 PM
  #19  
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fuel problem????

okay guys, I am about to expose my internal engine lack of knowledge but here goes.. I did compression checks on all 6 and if I did it right most were around 60 and the front 2 were 70 and about 75. I have only done this once with instructions from Chilton's so I hope I did it right. What is good or bad.. Also the new plugs I put in a few days back were totally covered in soot like crap...Is this engine toast????If it is, can a first timer rebuild it without going broke?????
Thanks, Jerry
 
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Old Sep 13, 2003 | 05:27 AM
  #20  
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fuel problem????

That's pretty low. When doing the compression test did you crank the engine over long enough to build maximum compression? Sometimes it can take more than a few cranks.
 
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Old Sep 13, 2003 | 08:50 PM
  #21  
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fuel problem????

When performing a comp. check the throttle should be wide open, it needs open air flow into the cylinders to get a proper reading. A common mistake, if you did that . Awful low readings.
It could be a defective vacuum advance also. Idle problems not the comp readings.
We all had a first engine rebuild, get a book on your engine and read up, ask questions, listen and learn. You can do it!!
An engine in good condition should have 120 to 150 psi, I have seen engines in good condition with lower readings but it isn't common or desirable.
 

Last edited by Putt; Sep 13, 2003 at 09:13 PM.
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Old Sep 13, 2003 | 10:59 PM
  #22  
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fuel problem????

Correct me if I'm wrong but, if the comp. test was done properly, does this sound like a motor with serious VALVE TIMING issues???
 
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Old Sep 13, 2003 | 11:03 PM
  #23  
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fuel problem????

You stated the plugs are new, but have soot on them now. Sounds like you're running too fat. Check your fuel air mixture and accelerator pump. When the engine bogs down, there's too much fuel being dumped down the carb. You didn't mention a backfire coming from the carb if you flip the throttle open, so chances are you're not running lean (lean = not enough fuel. fat/rich = too much fuel).
 
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Old Sep 14, 2003 | 12:12 AM
  #24  
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fuel problem????

Yes, either valve timing or seriously worn rings.
It does sound like it is rich with the sooty plugs so fast. How's the air filter?
 
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Old Sep 14, 2003 | 10:16 PM
  #25  
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fuel problem????

will try the comp check again with the throttle open... everyone keeps mentioning accelerator pump, but I have had the same problem with the carb that came on this truck, that carb rebuilt and float adjusted three times, and a new (rebuilt) one form napa. Could this indicate an engine (combustion)problem and not a fuel issue???I am pretty car repair savvy but I've taken all of hte suggestions out to the driveway and don't seem to be making progress.
....And I do appreciate all who are trying to help, Thanks Jerry
 
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Old Sep 14, 2003 | 11:50 PM
  #26  
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fuel problem????

It is sounding like an engine condition problem and not a tune-up issue. With that low of a comp., the plugs would color very fast. Do you see any blue smoke?
 
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Old Sep 15, 2003 | 02:07 AM
  #27  
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fuel problem????

If your compression readings are correct it is amazing it even runs at all. It's time to yank it out and tear it down, or at least pull the front cover and check the timing chain.
 
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Old Sep 15, 2003 | 08:43 AM
  #28  
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fuel problem????

Pardon, but the 300 I6 does not have a timing chain, it has two gears. It is nearly impossible for the valve timing to go bad. I think the engine is worn out.
 
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Old Sep 15, 2003 | 02:32 PM
  #29  
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fuel problem????

OOPS!! sorry, this thread has been going so long I forgot that it was about a 300-6.
 
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Old Sep 16, 2003 | 12:05 AM
  #30  
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fuel problem????

MY 29 cents worth....I don't see how an engine that is shot could idle perfectly and even rev normally at times. My gut hunch is the compression readings are off. Maybe didn't crank enough, or have a good seal? Soot? It's running too rich at some point. My gut hunch at this point? Check fuel pressure. it may be too high. This is fairly common on those engines and carbs. And it would probably act about as you describe. Run good until the float needle gets blown off it's seat from the *maybe* excess pressure. Will then run way to rich. This would explain the soot.
You can buy inline regulators. Offhand, I think the engine is usable. I sure wouldn't be in a hurry to tear it apart without further checking. A bad engine shouldn't be capable of ever running right. This one seems to sometimes. MK
 
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